The first
statement on possible existence of a narrow nucleon resonance near 1680
MeV was based on the π
Ν Partial Wave Analysis, though it suggested very small coupling
with the π Ν channel.
Then direct experimental evidences for the narrow bump in this mass area
have been reported in the η
photoproduction by three independent groups, first by GRAAL, and
somewhat later by CB-ELSA and LNS.

The resonance
interpretation imply unfamiliar features: a small total width (< 25
MeV), very small π Ν
coupling, and strong isotopic asymmetry of photocoupling (production
off neutron at least an order higher than off proton). These properties
are very similar to those predicted for the non-strange member of the
exotic anti-decuplet.

Alternative explanations of the observed bumps in terms of interference
of known nucleon resonance have been suggested as well. It seems that,
despite intensive studies of baryon spectroscopy world wide, we may have
earlier missed a narrow nucleon resonance with mass around 1680 - 1690
MeV.

Therefore, the situation is worth a profound discussion, which may clarify
the present status and suggest new directions for both experimental and
theoretical investigations.

May
the Chiral Soliton Approach present an adequate model for complete
QCD description of baryons?

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